Solana targets 150ms transaction finality with Oct. 21 upgrade

October 21 is reserved for the launch of Alpenglow, a protocol upgrade that aims to guarantee an irrevocable transaction in less than 150 milliseconds and remove the TowerBFT voting system the platform has used since 2020.

Why the speed of finality matters

While a Solana transaction may already become successful instantaneously, the difference is in the guarantee that stands behind it.

The Alpenglow protocol is designed to provide a near-instant guarantee that the finalized transaction is immutable. The real benefit will be received by the parties who need certainty to do something, such as a merchant who releases their goods or a cross-chain bridge that unlocks funds on a different blockchain. They may proceed faster.

The 150 milliseconds target is a projection rather than a promise, and actual performance will depend on the network conditions. Solana price stood around $104 on October 14, with its market cap standing at $61.3 billion.

How the voting change works

Currently, the validators who confirm transactions and validate the Solana network vote via on-chain transactions. Using the Alpenglow protocol, they can exchange these votes and collect a sufficient number of votes into a certificate to finalize a block after one or two rounds.

It’s time.

Alpenglow goes live on mainnet-beta Wednesday, October 21, ~14:50 UTC.

18 months of work for a migration that happens in one slot. Finality drops from seconds to ~150ms.

Make sure to follow us @anza_xyz as we countdown to go-live.

Details: https://t.co/MEf26uzCMW

— Anza (@anza_xyz) October 13, 2026

This process is said to be replacing TowerBFT and is named Votor, which was designed to reduce both the latency and cost associated with validators’ voting.

There is an unintended consequence worth pointing out. Since votes are not recorded anymore in blocks, the total number of transactions on Solana could fall dramatically on the launch day of the Alpenglow protocol, despite the same volume of trading and payments.

What validators have to do

Agave 4.3.0-based software is needed for operators to make the move. Two competing validator clients, namely Firedancer and Frankendancer, will not be able to assist in the initial migration and therefore will have to use another client temporarily.

Also, the economic model changes as well: validators currently pay around 1 SOL per epoch as voting fees; now this cost will change to the fixed admission fee of 0.8 SOL. An epoch is the period during which Solana assigns validator roles.

The activation schedule

The migration is supposed to happen during epoch 1064 and should begin somewhere at 15:00 UTC on October 21. The network will continue to use the current voting process for the first 5,000 slots, short timeframes allocated for block production, and will switch to Alpenglow approximately 18 minutes after that. It was also noted by The Defiant that the date for mainnet migration is October 21.

Possible problems with the mainnet migration may have an impact on sentiment; however, prediction market pricing suggests that there is no considerable effect expected from it yet.

If you're reading this, you’re already ahead. Stay there with our newsletter.